Individuals with physical impairments can experience difficulty in seating and unseating themselves in a chair or bench without assistance. This can be the result of a wide variety of temporary or permanent physical impairments, including the loss of a leg or foot, reduced leg strength due to injury, disease or atrophy, reduced flexibility due to arthritis, etc. Such impairments can render one unable to stand up from a chair unassisted and can make it very difficult to sit down safely in the chair.
This problem has been addressed in the art by the development of chairs having a power-driven seat bottom for lifting an individual to help him or her out of the chair, the power being provided by electric, pneumatic or hydraulic means. Chairs or seating assistance devices with power-driven seat bottoms are shown in the following U.S. Pat. Nos.: 3,479,087 to Burke; 3,623,767 to Condon; 4,690,457 to Poncy et al; 4,777,671 to Kearns: and, 4,884,841 to Holley. Such arrangements generally suffer from a need for access to a source of power, making portable use less convenient. These types of devices also tend to be expensive and heavy. Furthermore, these tend to lift the person at a predetermined rate, thereby making it difficult for the person to control the amount of assistance provided during the lifting. In addition, electrifying a chair on which the physically impaired person is sitting, and from which the person might not be able to escape without assistance, introduces a safety hazard to the person. The same is true, to a lesser degree, in the case of hydraulically driven assist devices.
Spring-assisted arrangements have also been provided for helping physically impaired persons in and out of chairs and have the advantage of not requiring electricity or hydraulic actuation, thus removing the safety hazard inherent in these arrangements. Such known spring-assisted arrangements usually include a base frame affixed to or forming part of a frame of the chair, an upholstered seating members pivotally mounted to the base frame and one or more springs for urging the seating member from a lowered position toward a raised, generally tilted position. Arrangements of this type are generally shown in the following U.S. Pat. Nos.: 3,039,818 to Frank; 3,158,398 to Stryker: 4,538,853 and 4,573,736 to Levenberg: and 4,852,849 to Jones. Because the frame of the spring-assisted device usually is specially adapted for attachment to a particular chair or forms an integral part of the chair, known devices of this type have not been well suited to being moved from one chair to another.
Known spring-assisted arrangements typically have a latch mechanism for releasably securing the seating member in the lowered position and for releasing the seating member to allow the springs to provide assistance for unseating and seating. These known latch mechanisms generally suffer from being awkward to operate and they can require that the user operate the latch mechanism during at least part of the user's ascent from the chair. However, it is desirable that the user's hands be free during ascent and descent in order to allow the user to balance himself or herself and to allow the user to hold on to the chair or other nearby items for additional support. As the latching mechanism is to be operated by a person with a physical impairment, it is important that it be easily and reliably operable.
Accordingly, it is seen that a need yet remains for a lift apparatus which can be mounted on a chair, moved from one chair to another and easily operated by the user while leaving the user's hands free during ascent. It is to the provision of such therefore that the present invention is primarily directed.